Search

In 2004, European Space Agency launched the spacecraft Rosetta. After almost 10-yr flight it arrived at the Churyumova–Gerasimenko comet. Rosetta was orbiting about the comet for some time observing its environment. One of the most interesting observations obtained during this mission was multiple disappearance of magnetic field. It was suggested that this phenomenon is related to the instability of cometopause, which is a tangential discontinuity separating the solar wind flow from the plasma component of the flow from a comet. In this article, we aim to study this instability. We numerically calculated the stationary state with the account of charge exchange on water molecules and resonant charge exchange. Then, we solved the non-stationary problem using the stationary state as the initial condition. We also studied the stability of the cometopause analytically in the short-wavelength approximation where we substituted the curved cometopause by a tangent plane. Both the numerical and analytical results show that the velocity jump at the cometopause is too weak to overtake the stabilizing effect of the magnetic field and cause the Kelvin–Helmholtz instability. We conclude that the main course of the cometopause instability is the charge exchange, and the instability is similar to the Rayleigh–Taylor instability that occurs in a gravitational field. [ABSTRACT FROM AUTHOR]

We study kink oscillations of a straight magnetic tube with a transitional region at its boundary. The tube is homogeneous in the axial direction. The plasma density monotonically decreases in the transitional region from its value inside the tube to that in the surrounding plasma. The plasma motion is described by the linear magnetohydrodynamic equations in the cold plasma approximation. We use the ideal equations inside the tube and in the surrounding plasma, but take viscosity into account in the transitional region. We also use the thin tube and thin transitional or boundary layer (TTTB) approximation. Kink oscillations are assumed to be driven by a driver at the tube footpoint. We derive the equation describing the displacement in the fundamental mode and overtones. We use this equation to study kink oscillations in both the case of harmonic and random driving. In the case of random driving, we assume that the driver is described by a stationary random function. The displacements in the fundamental mode and overtones are also described by stationary random functions. We derive the relation between the power spectra of the fundamental mode and all overtones and the power spectrum of the driver. We suggest a new method of obtaining information on the internal structure of coronal magnetic loops based on the shape of graphs of the power spectrum of the fundamental mode. [ABSTRACT FROM AUTHOR]

We study damping of phase-mixed Alfvén waves propagating in non-reflective axisymmetric magnetic plasma configurations. We derive the general equation describing the attenuation of the Alfvén wave amplitude. Then we applied the general theory to a particular case with the exponentially divergent magnetic field lines. The condition that the configuration is nonreflective determines the variation of the plasma density along the magnetic field lines. The density profiles exponentially decreasing with the height are not among non-reflective density profiles. However, we managed to find non-reflective profiles that fairly well approximate exponentially decreasing density.We calculate the variation of the total wave energy flux with the height for various values of shear viscosity. We found that to have a substantial amount of wave energy dissipated at the lower corona, one needs to increase shear viscosity by seven orders of magnitude in comparison with the value given by the classical plasma theory. An important result that we obtained is that the efficiency of the wave damping strongly depends on the density variation with the height. The stronger the density decrease, the weaker the wave damping is. On the basis of this result, we suggested a physical explanation of the phenomenon of the enhanced wave damping in equilibrium configurations with exponentially diverging magnetic field lines. [ABSTRACT FROM AUTHOR]

Aims. In the present study we investigate the nature of the magnetic Rayleigh-Taylor instability appearing at a tangential discontinuity in a partially ionised plasma when the effect of magnetic shear is taken into account. Methods. The partially ionised character of the plasma is described by the ambipolar diffusion in the induction equation. The dynamics of the plasma is investigated in a single-fluid approximation. After matching the solutions on both sides of the interface we derive a dispersion equation and calculate the instability increment using analytical methods for particular cases of parameters, and numerical investigation for a wide range of parameters. Results. We calculated the dependence of the instability increment on the perturbation wavenumber. We also calculated the dependence of the maximum instability increment on the shear angle of the magnetic field for various values of the ionisation degree. Conclusions. Our results show that the Rayleigh-Taylor instability becomes sensitive to the degree of plasma ionisation only for plasmas with small values of plasma beta and in a very weakly ionised state. Perturbations are unstable only for those wavenumbers that are below a cut-off value. [ABSTRACT FROM AUTHOR]

Background: A central challenge to precision medicine research efforts is the return of genetic research results in a manner that is effective, ethical, and efficient. Formal tests of alternate modalities are needed, particularly for racially marginalized populations that have historically been underserved in this context., Methods: We are conducting a randomized controlled trial (RCT) to test scalable modalities for results return and to examine the clinical utility of returning genetic research results to a research cohort of Black women. The primary aim is to compare the efficacy of two communication modalities for results return: 1) a conventional modality that entails telephone disclosure by a Board-certified genetic counselor, and 2) an online self-guided modality that entails results return directly to participants, with optional genetic counselor follow-up via telephone. The trial is being conducted among participants in the Black Women's Health Study (BWHS), where targeted sequencing of 4000 participants was previously completed., Results: Several ethical, legal, and social implications (ELSI) and challenges presented, which necessitated substantial revision of the original study protocol. Challenges included chain of custody, re-testing of research results in a CLIA lab, exclusion of VUS results, and digital literacy. Bioethical principles of autonomy, justice, non-maleficence, and beneficence were considered in the design of the study protocol., Conclusion: This study is uniquely situated to provide critical evidence on the effectiveness of alternative models for genetic results return and provide further insight into the factors influencing access and uptake of genetic information among U.S. Black women., Clinicaltrials: gov: NCT04407611., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Children adopted from foster care are at heightened risk for emotional and behavioral challenges, potentially due to early trauma exposure and related risk factors. Research has demonstrated that adoptees with greater pre-adoptive risk exhibit higher rates of internalizing and externalizing problems across childhood and into adulthood. However, these studies have been limited by their use of individual risk factors or sum scores of cumulative risk and their measurement of internalizing and externalizing behaviors separately., Objective: The current study aimed to examine effects of pre-adoptive risk on long-term functioning in children adopted from foster care., Method: In a longitudinally-followed sample of 82 adoptees, we utilized latent growth curve modeling to examine effects of two latent indices of pre-adoptive risk, postnatal (i.e., trauma-related) risk and prenatal risk (not including prenatal substance exposure, since it was nearly ubiquitous in this sample), on adoptee internalizing, externalizing, and latent scores of dysregulation across childhood. Additionally, in three separate models, we tested whether baseline levels and change across childhood in internalizing, externalizing, and dysregulation mediated effects of prenatal and postnatal risk on adolescent/young-adult functioning., Results: Greater postnatal risk, but not prenatal risk, predicted higher levels of internalizing and dysregulation across childhood. However, only dysregulation mediated the effect of postnatal risk on adolescent/young-adult functioning., Conclusions: These results are consistent with prior research evidencing long-term effects of postnatal pre-adoptive risk, but not prenatal risk, in adoptees. Furthermore, they suggest that trauma exposure in this population may result in a profile of broad dysregulation that increases risk for maladjustment into adulthood., (Copyright © 2021. Published by Elsevier Ltd.)

Many transgender individuals want to have children and are pursuing reproductive care. Limited research has described the experiences of transgender individuals during pregnancy, and no known studies have examined reproductive genetic counseling sessions with this patient population. To understand what topics and considerations are explored within this sector of reproductive care, prenatal and preconception genetic counselors that have seen a transgender patient and/or transgender partner of a patient were recruited through an email blast to members of the National Society of Genetic Counselors. Nine genetic counselors completed phone interviews. Content analysis was used to identify, quantify, and examine the concepts within the transcripts. Six major themes emerged: (1) Trans individuals were referred for common genetic counseling indications, (2) genetic counselors were driven to think of more inclusive language, (3) genetic counselors considered ways to make written materials more inclusive, (4) trans individuals expressed discomforts in the prenatal/preconception setting, (5) genetic counselors observed challenges with the care team, and (6) genetic counselors felt underprepared. This study identifies areas within reproductive spaces of genetic counseling that could be more inclusive, particularly relating to commonly used gendered language and written materials, and provides training recommendations for genetic counselors. Additionally, we outline the reported areas of discrimination for these patients and partners, and discuss ways that genetic counselors can be advocates for respectful and equitable care within their clinics., (© 2021 National Society of Genetic Counselors.)

Introduction: Despite universal newborn screening (NBS), children in the U.S. continue to experience morbidity and mortality from sickle cell disease and related causes. Recognizing that assessments of public health services and systems can improve public health system performance and ultimately health outcomes, this study examined variations in NBS program activities for sickle cell disease., Methods: A mixed methods study included (1) a 2009 survey of NBS programs based on ten essential public health services (N=39 states with ten or more sickle cell births over a 3-year period) and (2) key informant interviews in 2011 with 13 states that had sufficient Phase 1 survey scores, black births, and variability in state legislation and geography. Key informants were from 13 NBS programs, 22 sickle cell treatment centers, and ten advocacy organizations. Analyses were conducted in 2009-2014., Results: Considerable variability exists across states in program activities and roles. More programs reported activities oriented to care of individuals-ensuring access to services, coordination, and provider education; fewer reported planning and analysis activities oriented to statewide policy development and system change. Numbers of activities were not related to the number of affected births. In-depth interviews identified opportunities to enhance activities that support statewide comprehensive systems of care., Conclusions: NBS programs perform important public health roles that complement and enhance clinical services. Nationwide efforts are needed to enable NBS programs to strengthen population-based functions that are essential to ensuring quality of care for the entire population of children and families affected by sickle cell disease., (Copyright © 2016 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.)

Maternal and child health (MCH) leadership requires an understanding of MCH populations and systems as well as continuous pursuit of new knowledge and skills. This paper describes the development, structure, and implementation of the MCH Navigator, a web-based portal for ongoing education and training for a diverse MCH workforce. Early development of the portal focused on organizing high quality, free, web-based learning opportunities that support established learning competencies without duplicating existing resources. An academic-practice workgroup developed a conceptual model based on the MCH Leadership Competencies, the Core Competencies for Public Health Professionals, and a structured review of MCH job responsibilities. The workgroup used a multi-step process to cull the hundreds of relevant, but widely scattered, trainings and select those most valuable for the primary target audiences of state and local MCH professionals and programs. The MCH Navigator now features 248 learning opportunities, with additional tools to support their use. Formative assessment findings indicate that the portal is widely used and valued by its primary audiences, and promotes both an individual's professional development and an organizational culture of continuous learning. Professionals in practice and academic settings are using the MCH Navigator for orientation of new staff and advisors, "just in time" training for specific job functions, creating individualized professional development plans, and supplementing course content. To achieve its intended impact and ensure the timeliness and quality of the Navigator's content and functions, the MCH Navigator will need to be sustained through ongoing partnership with state and local MCH professionals and the MCH academic community.